Final Fantasy IV since it was the first Final Fantasy game I played and has my favourite Final Fantasy boss and battle themes. I also like FF6 even though I've just started it and it feels a bit more lighthearted than the others.

VII and XIII were the only ones I have bothered to finish, xiii was kinda of a tube run but it had great battle system, where vii had a super awesome story and characters. I've never liked ff that much, turn based combat is too easy and slow. I played X pretty far but then the story just turned out shit and I hated how they just gave you all the info so fast and the characters were pretty shit :P. The beginning was really really promising though and got me all excited but then it just flattened Oh and aurion was cool!